A recording apparatus, such as a copying machine, a printer, a facsimile machine, or a multifunction printer having copying, printing, scanning, and facsimile functions, forms an image on a recording medium (for example, a sheet) with ink and according to image data. For example, an ink droplet is discharged from a nozzle of a recording head. While the recording head moves in a main scanning direction, the recording head discharges an ink droplet onto a sheet to form an image on the sheet.
Generally, the recording head discharges an ink droplet by a bubble jet method, a piezo jet method, or a liquid droplet jet method. In the bubble jet method, a heater heats the ink to generate a bubble. A pressure of the bubble discharges an ink droplet from the recording head. In the piezo jet method, an ink droplet is discharged by an electric and mechanical displacement of a bulk of a piezoelectric element. In the liquid droplet jet method, a micro fluid element and a surface acoustic wave propagate in the ink to cause ejection of an ink droplet. In the bubble jet method, the piezo jet method, and the liquid droplet jet method, electric power of from 0.1 watts to several watts is needed, resulting in migration and a broken wire.
To address the above-described problems, the recording head includes a liquid droplet discharging head circuit board in which a protective layer is formed on a wiring pattern. FIGS. 1 and 2 illustrate a liquid droplet discharging head circuit board 100R of the recording head. FIG. 1 is a plane view of the liquid droplet discharging head circuit board 100R. FIG. 2 is a sectional view of the liquid droplet discharging head circuit board 100R taken along line A1-A1 of FIG. 1. As illustrated in FIGS. 1 and 2, the liquid droplet discharging head circuit board 100R includes a board 1R, an oxide film 2R, an electricity-heat conversion element 3R, and a wiring pattern 4R. As illustrated in FIG. 2, the liquid droplet discharging head circuit board 100R further includes a first protective layer 5R and a second protective layer 6R.
The board 1R includes silicon. The oxide film 2R is formed on the board 1R. The electricity-heat conversion element 3R includes a heat-generating resistance body film formed at a predetermined position on the oxide film 2R and having a predetermined size. The electricity-heat conversion element 3R serves as a discharging energy generating element. The wiring pattern 4R is formed on the oxide film 2R and has a predetermined pattern. The wiring pattern 4R electrically connects the electricity-heat conversion element 3R to a power source (not shown) to supply power to the electricity-heat conversion element 3R. The first protective layer 5R is formed on the electricity-heat conversion element 3R and the wiring pattern 4R to cover the electricity-heat conversion element 3R and the wiring pattern 4R, and includes an insulating material. The second protective layer 6R is formed on the first protective layer 5R and includes an insulating material. The wiring pattern 4R includes a broad band conductive film having a substantially constant thickness. A width W1 of the wiring pattern 4R is not smaller than about 10 μm, for example.
The first protective layer 5R can reduce migration. However, the first protective layer 5R cannot directly prevent a broken wire of the wiring pattern 4R.